A form-fill-seal machine provided with an ultrasonic sealing device is conventionally used as a form-fill-seal machine for forming a bag from a film-shaped packaging material and filling the bag with candy or another object to be bagged, as shown in Japanese Unexamined Patent Application Publication No. 2001-233309. The ultrasonic sealing device applies fine ultrasonic vibrations to the thermoplastic packaging material to cause the packaging material to fuse, and applies pressure to the packaging material to seal the packaging material. The ultrasonic sealing device usually sandwiches the packaging material using two metal components referred to as a horn and an anvil, and seals the packaging material using ultrasonic vibrations transmitted to the horn by an ultrasonic transmitter.